1. Field of the Invention
The present invention relates to a hard material insert for a drill and, in particular, a drill for drilling in a reinforced concrete, and to a drill with such an insert.
2. Description of the Prior Art
The problem with the drills of the type discussed above consists in that they should meet contradictory requirements. On one hand, the drills should be formed sufficiently hard for removal of a brittle stone material. On the other hand, the drills should be formed sufficiently ductile to insure their robustness upon encounter with concrete reinforcement. Together with the selection of a corresponding material, the shape of the hard material insert assumes a particular importance in this regard, with at least one aspect consisting in the optimization of the manufacturing process during which a material-locking connection of the hard material insert with a drilling head of a drill should be effected at narrowly limited optimal conditions in order, e.g., to minimize temperature-induced latent stresses and unbalances.
U.S. Pat. No. 5,287,937 or European Publication EP 790387 discloses a mirror-symmetrical, plate-shaped hard material insert with two opposite radial arms on which cutting edges are formed, and with a central reinforcement in form of a segment of a cylinder. The insert is self-adjustable upon being brazed in the drill head.
U.S. Pat. No. 3,447,616 discloses a plate-shaped hard material insert with a central reinforcement in form of a segment of a cylinder and that does not extend over the entire axial length.
German Publications DE 196 50 487 and DE 197 24 373 disclose a compact prismatic hard material insert with an X-shaped cross-section.
U.S. Design Patent No. 515,116 S discloses a hard material insert for a drill having in its cross-section extending transverse to a rotational axis of the drill, an axially central reinforcement, and two diametrically opposite, radial arms each having a cross-section tapering radially outwardly, opposite free side and connection side, with the free and connection sides of one of the radial arms being arranged alternatively with respect to the free and connection sides of another of the radial arms.
An object of the present invention is to provide a hard material insert for a drill and suitable for mass production.
Another object of the present invention is to provide a hard material insert optimal for drilling in a reinforced concrete.